[The materials engineering characteristics of orthodontic nickel-titanium wires].
Since their introduction in 1971 nickel-titanium wires have been widely used in orthodontics. Today, there is a multitude of new NiTi-alloys, whose properties are described. Beside the memory effect, these alloys have particular elastic properties, which can be characterized by a low modulus of elasticity, excellent springback, and pseudoelasticity (superelasticity). These properties are a consequence of the fact that depending on temperature and mechanical stress NiTi-alloys have two crystalline structures: martensite and austenite. The transition between these two phases, called martensitic transformation, is responsible for the memory effect, where a one way and a two way effect can be distinguished. For orthodontic applications pseudoelasticity is regarded as a highly favourable property. Pseudoelastic behavior is caused by stress induced martensite. Analysing the elastic properties of the available wires two categories can be distinguished: "work hardened martensite" and "pseudoelastic alloy". The biocompatibility of NiTi is sufficient, it can be used as an implant material.
Drescher
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D
Poliklinik für Kieferorthopädie, Rheinische Friedrich-Wilhelms-Universität Bonn.
Bourauel
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C
Thier
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M
D003461:Crystallography; D004548:Elasticity; D008422:Materials Testing; D008669:Metallurgy; D009532:Nickel / Q000737:chemistry*; D009969:Orthodontic Wires; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry*
C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
Materialtechnische Besonderheiten orthodontischer Nickel-Titan-Drähte.